Infinitely variable transmission ratio drives, formed by cone pulleys which can be spread apart, more or less, to vary the radial position of a chain engaging between facing cone pulleys are noisy. Much work has been done to reduce operating noise, and to reduce oscillations which occur upon engagement of the chain links and/or the connecting elements with the cones of the cone pulley. Such oscillations arise, for example, upon impingement of a chain element with the cone pulleys. These impingement forces cause shocks which not only result in noise of operation but, also, reduce the lifetime of the transmission.
It has been proposed to replace hinge pins connecting links of a link chain, such as a plate link chain similar to a sprocket chain by rocker elements, the rocker elements forming the hinge joints to permit the hinges of the chain to flex with respect to each other, and thus wrap between the cone pulleys. Reference is made to German Pat. No. 1,065,685, and specifically to U.S. Pat. No. 4,344,761, STEUER, and the referenced applications U.S. Ser. No. 285,869, filed July 21, 1981, RATTUNDE and SCHOPF, and application U.S. Ser. No. 402,457, filed July 28, 1982, RATTUNDE, the inventor hereof, the disclosures of the U.S. patent applications being hereby incorporated by reference. For example, it has been proposed to change the division or pitch ratio of the links so as to be non-uniform by providing for different distances between link elements; it has also been proposed to reduce the distances between joints, that is, to increase the pitch of the chain by suitable formation of the links and the rocker elements which engage therewith. All these efforts have resulted in substantial reduction of oscillation and, hence, noise level occurring in operation.
It has previously been proposed--see German Patent Disclosure Document DE-OS No. 31 09 265--to include loading blocks between joint connections, which are used to transmit frictional forces. The placement of these loading blocks, and their pitch, with respect to the chain, depends on the pitch of the joints of the chain. The joints do not participate in the transmission of frictional forces; placement of such additional loading or friction blocks, thus, does not improve the noise level and vibration level since the pitch of the chain links that is, the number of blocks per unit length, is not increased over that of a chain which does not have such blocks.